The complex [FeSCN]2+ has an absorptivity of 6.14×10−2 L/(mg⋅cm) at a wavelength of 580 nm. The transmittance of a solution sample was measured in a 1.00 cm cell, and the percent transmittance %T was 53.9%. Calculate the concentration of the solution in ppm.

4.36 ppm

Explanation:

First we convert percent transmittance to absorbance:

Then we calculate the concentration of the solution, using Lambert-Beer's equation:

It is usually used with molar concentrations but given that the given absortivity is in ppm terms and the answer is also in ppm, we can simply use the given value.